<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
    <h1>{{info}}</h1>
</div>

<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
    let v = new Vue({
        el:"#app",
        data:{
            info:"Hello Vue!"
        }
    })

    setTimeout(function () {
        v.info = "bye Vue!"
    },2000)
</script>
</body>
</html>